1. Field of the Invention:
The present invention relates to a method and an apparatus for inspecting castings produced by a die-casting machine for defects, such as internal defects, by monitoring operating conditions of the die-casting machine.
2. Description of the Prior Art
Aluminum die-castings produced by a die-casting machine have heretofore been inspected for casting defects, particularly internal defects, generally by means of an X-ray or ultrasonic inspection apparatus which is quite expensive and requires many inspection steps. Such an inspection process is normally carried out on a number of castings grouped as a lot subsequently to the diecasting process. Therefore, there is a tendency in such an inspection that even when defective products are produced due to improper operating conditions, such as die mold temperature, molten-metal temperature, plunger tip speed, counterplunger tip displacement, relative position and speed between the plunger and counterplunger tips, and the like, resulting from malfunctioning of the die-casting machine, such defective castings are found only in a later inspection process and a relatively long period of time is thus needed to detect defective castings with the result that many unwanted defective products continue to be produced until detection of the defect. With the time lag of detection of defective castings during production thereof, some improper operating conditions are liable to return to normal during the time lag. Thus, it is often difficult to detect the cause of such imperfect castings and hence no measure can easily be taken for reliably preventing the production of more of such defective castings.
The present invention has been made in an effort to eliminate the foregoing problems.